FileHandle(3)

NAME
FileHandle - supply object methods for filehandles

SYNOPSIS
    use FileHandle;
    $fh = new FileHandle;
    if ($fh->open("< file")) {
        print <$fh>;
        $fh->close;
    }
    $fh = new FileHandle "> FOO";
    if (defined $fh) {
        print $fh "bar\n";
        $fh->close;
    }
    $fh = new FileHandle "file", "r";
    if (defined $fh) {
        print <$fh>;
        undef $fh;       # automatically closes the file
    }
    $fh = new FileHandle "file", O_WRONLY|O_APPEND;
    if (defined $fh) {
        print $fh "corge\n";
        undef $fh;       # automatically closes the file
    }
    $pos = $fh->getpos;
    $fh->setpos($pos);
    $fh->setvbuf($buffer_var, _IOLBF, 1024);
    ($readfh, $writefh) = FileHandle::pipe;
    autoflush STDOUT 1;

DESCRIPTION
NOTE: This class is now a front-end to the IO::* classes.

"FileHandle::new" creates a "FileHandle", which is a reference to a newly created symbol (see the "Symbol" package). If it receives any parameters, they are passed to "FileHandle::open"; if the open fails, the "FileHandle" object is destroyed. Otherwise, it is returned to the caller.

"FileHandle::new_from_fd" creates a "FileHandle" like "new" does. It requires two parameters, which are passed to "FileHandle::fdopen"; if the fdopen fails, the "FileHandle" object is destroyed. Otherwise, it is returned to the caller.

"FileHandle::open" accepts one parameter or two. With one parameter, it is just a front end for the built-in "open" function. With two parameters, the first parameter is a filename that may include whitespace or other special characters, and the second parameter is the open mode, optionally followed by a file permission value.

If "FileHandle::open" receives a Perl mode string (">", "+<", etc.) or a POSIX fopen() mode string ("w", "r+", etc.), it uses the basic Perl "open" operator.

If "FileHandle::open" is given a numeric mode, it passes that mode and the optional permissions value to the Perl "sysopen" operator. For convenience, "FileHandle::import" tries to import the O_XXX constants from the Fcntl module. If dynamic loading is not available, this may fail, but the rest of FileHandle will still work.

"FileHandle::fdopen" is like "open" except that its first parameter is not a filename but rather a file handle name, a FileHandle object, or a file descriptor number.

If the C functions fgetpos() and fsetpos() are available, then "FileHandle::getpos" returns an opaque value that represents the current position of the FileHandle, and "FileHandle::setpos" uses that value to return to a previously visited position.

If the C function setvbuf() is available, then "FileHandle::setvbuf" sets the buffering policy for the FileHandle. The calling sequence for the Perl function is the same as its C counterpart, including the macros "_IOFBF", "_IOLBF", and "_IONBF", except that the buffer parameter specifies a scalar variable to use as a buffer. WARNING: A variable used as a buffer by "FileHandle::setvbuf" must not be modified in any way until the FileHandle is closed or until "FileHandle::setvbuf" is called again, or memory corruption may result!

See the perlfunc manpage for complete descriptions of each of the following supported "FileHandle" methods, which are just front ends for the corresponding built-in functions:

    close
    fileno
    getc
    gets
    eof
    clearerr
    seek
    tell
See the perlvar manpage for complete descriptions of each of the following supported "FileHandle" methods:

    autoflush
    output_field_separator
    output_record_separator
    input_record_separator
    input_line_number
    format_page_number
    format_lines_per_page
    format_lines_left
    format_name
    format_top_name
    format_line_break_characters
    format_formfeed
Furthermore, for doing normal I/O you might need these:

$fh->print
    See the print entry in the perlfunc manpage.

$fh->printf
    See the printf entry in the perlfunc manpage.

$fh->getline
    This works like <$fh> described in the I/O Operators entry in the perlop manpage except that it's more readable and can be safely called in a list context but still returns just one line.

$fh->getlines
    This works like <$fh> when called in a list context to read all the remaining lines in a file, except that it's more readable. It will also croak() if accidentally called in a scalar context.

There are many other functions available since FileHandle is descended from IO::File, IO::Seekable, and IO::Handle. Please see those respective pages for documentation on more functions.

SEE ALSO
The IO extension, the perlfunc manpage, the I/O Operators entry in the perlop manpage.